Chapter 6: Population Biology

Question 1

What is biotic potential?

Answer 1

The maximum reproductive rate of an organism; given unlimited resources and ideal environmental conditions.

Question 2

What is a carrying capacity?

Answer 2

The number or biomass of a species that can be supported without depleting resources.

Question 3

When food and resources deplete, what happens?

Answer 3

A population crash occurs.

Question 4

What shape does an exponential growth rate model look like? Describe the model.

Answer 4

It has a J shape curve. This model describes when the population increases above the carrying capacity and suffers a population crash. The population decreases restarts the J shaped curve.

Question 5

What is the shape of a logistic growth curve? What does the graph means.

Answer 5

It forms an S shape. The population of a community increases similar to a exponential curve, except when you reach the middle of the S, the rate of increase decreases and the population doesn’t exceed the carrying capacity.

Question 6

Logistic growth is dependent on what factor?

Answer 6

Logistic growth is dependent on population density.

Question 7

Name some examples of density independent factors.

Answer 7

Ususally abiotic factors like fires or drought.

Question 8

What is an “r-selected” species? And what model discussed earlier can they relate to?

Answer 8

Employ a high reproductive rate to overcome the high mortality of offspring. (Housefly) These species can relate to the exponential model.

Question 9

What is a “K-selected” species? And what model discussed earlier can they relate to.

Answer 9

Reproduce conservatively with longer generation times and fewer young. (Humans) These species can relate to the logistic growth model.

Question 10

What is the equation for the rate of growth?

Answer 10

(B+I) – (D+E) = rate of growth; B = Births, D = Deaths, I = immigrants, E = emigrants

Question 11

What is Total Fertility Rate?

Answer 11

Average number of offspring born to a female in her lifetime.

Question 12

What is Replacement-Level Fertility?

Answer 12

Average number of offspring a mating pair must bear to replace themselves in a population. (Slightly over 2 per couple)

Question 13

What is Mortality?

Answer 13

Death Rate

Question 14

What is Natility?

Answer 14

Birth Rate

Question 15

How many types of survivorship are there? What are they?

Answer 15

There are 3 types of survivorship. The first is where organisms have a high juvenile survival rate and tend to reach old age. The second is where the probability of death is unrelated to age. The third is where organisms are very susceptible to death early in life, but if they make it to adulthood, they will probably live to the maximum life span.

Question 16

What are Intrinsic factors?

Answer 16

Factors from within a single population

Question 17

What are Extrinsic factors?

Answer 17

Imposed from outside the population

Question 18

What are Biotic factors?

Answer 18

Caused by living organisms; tend to be density dependent (effects are stronger when population density increases)

Question 19

What are Abiotc factors?

Answer 19

Caused by environmental or non-living components; tend to be density independent (effects are the same regardless of population density)

Question 20

Name some interspecific interactions.

Answer 20

Predator-Prey relationships, mutualism, commensalism

Question 21

Predator Prey relationships are always bad for the prey species. True or False. Explain.

Answer 21

False. Example: A moose population can be strengthened because the old and sick moose will be eaten by the wolves, and the healthy and young moose will survive and reproduce.

Question 22

Name some intraspecific interactions.

Answer 22

Territoriality.

Question 23

What is Territoriality?

Answer 23

Fighting to prove resources belong to a particular individual in a population. Territorial displays are often linked to mating rituals (dancing or singing ability, best colors, etc.). It is also related to fighting equipment (teeth, claws, antlers, horns, etc.)

Question 24

What are Stress-Related diseases (stress shock)?

Answer 24

Due to too much competition for resources or limited living space. This leads to lower fertility, less disease resistance, and pathological behavior.

Question 25

What is Island Biogeography?

Answer 25

The study of rates of colonization and extinction of species on islands or isolated areas based on size, shape, and distance from other inhabited regions. *Note: Biodiversity increases with an increase in island size and closeness to mainland

Question 26

What is Genetic Drift?

Answer 26

Gradual changes in gene frequencies due to random events.

Question 27

What is the Founder Effect?

Answer 27

(demographic bottleneck) - a few members of a species survive a catastrophic event or colonize a new habitat geographically isolated from members of the same species.

Question 28

What is Minimum Viable Population Size?

Answer 28

Number of individuals needed for longterm survival of a rare or endangered species. Example: for the grizzly bears the minimum viable population size is 100 bears.

Question 29

What is Metapopulation?

Answer 29

A population of populations that have regular or irregular gene flow between geographically separated units. Example: Butterfly patches in different locations.